Crushed Lava Rocks vs Perlite or Vermiculite

Can I just use crushed lava rocks mixed with clay and sand for the inside of the heat riser instead of perlite or vermiculite? I mean, perlite and vermiculite are both volcanic rocks, right?

"To oppose something is to maintain it" -- Ursula LeGuin

Ernie Wisner

gardener

Posts: 791

Location: Tonasket washington

31

posted 5 years ago

yep that they are however each has a specific insulation value. pumice being the lowest and perlite being the highest. in order to get the insulation values you have to use more materials. so you end up spending just as much to get 4 times the pumice as you would for a two 2 cubic foot of perlite.